Solve for $t$ : $10 = 25 + t$
Subtract $25$ from both sides: $ \begin{eqnarray} \\ \hphantom{10 {- 25}} &\hphantom{=}& \hphantom{t} \\ 10 &=& 25 + t \\ \\ {-25} && {-25} \\ \end{eqnarray} $ $ \begin{eqnarray} \\ 10 {- 25} &=& t \\ \end{eqnarray} $ Simplify. $ t = -15$